JP2001128417A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable heat radiation of a built-in type three-phase inverter which is made into an IC for realizing high output of motor. SOLUTION: A one-chip three-phase inverter 15, peripheral circuit 46, and Hall element sensor 7 are accommodated within a lower case 29 of a motor and each part accommodated within this lower case 29, except for the end part, where a detecting port of the Hall element sensor 7 is provided, is molded with a molding resin not illustrated in order to fix the position. Here, the one chip three-phase inverter 15 is allocated to assure sufficient heat radiation to the lower case 29 and this lower case 29 functions as the heat radiating means of the one-chip three-phase inverter 15. A motor is assembled through the setting of the upper case 17 and lower case 29 to a constant combination relationship by respectively inserting the lower surface pins 40A, 40B of the collar of upper case 17 into the holes 41A, 41B of the collar of the lower case 29.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor suitable for driving a fan of a room air conditioner, and more particularly to a brushless electric motor having a built-in inverter capable of variable speed control.

[0002]

2. Description of the Related Art A high-voltage one-chip three-phase inverter for controlling the number of revolutions of a motor by directly using a voltage obtained by rectifying and smoothing a 100 (V) commercial AC voltage as a power supply voltage. (Hereinafter referred to as one-chip three-phase inverter)
Was developed (for example, Nihon Dempa Shimbun on March 22, 1990). This one-chip three-phase inverter is extremely small in comparison with a conventional inverter, and can be built in a motor.

The element structure of this three-phase one-chip inverter is, as shown in FIG. 3A, based on polysilicon and by means of a dielectric isolation, that is, a high breakdown voltage area of each phase by a SiO ₂ phase. And a circuit for one phase is formed in each area.

FIG. 3B is a plan view showing a layout of each element of the one-chip three-phase inverter.

As is apparent from FIG. 1, six switching transistors 2 as main elements, a diode 1 for turning off a switching transistor 2 connected between a collector and an emitter of each switching transistor 2, and each switching transistor 2 Circuit 6 for forming a switching signal for turning on and off
And a drive circuit for driving each switching transistor 2 on and off with this switching signal, and detecting a current flowing through the switching transistor 2 to detect
The overcurrent protection circuit 5 for preventing the destruction of C and the internal power supply 4 are integrated into a single chip.

The size of an IC element of this one-chip three-phase inverter is 4.3 mm in length and 5.8 mm in width.

In such a one-chip three-phase inverter, a lateral IGBT is used as the switching transistor 2.
(Insulated Gate Bipolar Transistor) has greatly reduced the occupied area compared to conventional power MOSFETs,
A newly developed high-speed diode that can be realized by the same process as the GBT is employed, so that the reverse recovery current can be greatly reduced, and the switching loss of the switching transistor 2 due to the reverse recovery current can be greatly reduced. Also,
By incorporating a power supply circuit, only one external power supply is required to drive the switching transistor 2 as a power element. By incorporating an overcurrent protection circuit 5, an IC due to an excessive current generated due to a load short circuit or the like is provided. To prevent the destruction. Further, the inverter frequency is set to 20 kHz, which is higher than the audible frequency, so that motor noise can be significantly reduced.

FIG. 4 is a block diagram showing a conventional example of a brushless electric motor using such a one-chip three-phase inverter, wherein 7A, 7B and 7C are Hall element sensors, 8 is a sensor amplifier, and 9 is a rotation speed signal. Forming circuit, 10 is a speed correction circuit, 11 is a PWM (pulse width modulation) signal forming circuit,
12 is a starting current limiting circuit, 13 is an oscillation circuit, 14 is a stator, 15 is the one-chip three-phase inverter, and 16 is an external power supply.

Referring to FIG.
When the commercial AC voltage of (V) is applied, the external power supply 16
, A DC power supply voltage is applied to each circuit. This allows
The oscillation circuit 13 is activated, and the PWM signal forming circuit 11 generates a PWM signal at a predetermined cycle. The logic circuit 6
A three-phase switching signal is formed from the WM signal, and the drive circuit 3 sequentially turns on and off each switching transistor 2 according to the switching signal. As a result, a current flows in each coil provided on the stator 14 in a predetermined direction, a rotor (not shown) starts rotating, and the electric motor starts.

When the motor is started, a starting current limiting circuit 1
2 controls the PWM signal forming circuit 11 based on the detection result of the overcurrent protection circuit 5 so that the starting current flowing through each switching transistor 2 does not become excessive.
Adjust the duty ratio of the M signal.

The six switching transistors 2 are Q ₁ , Q ₂ , Q ₃ , Q ₄ , Q ₅ , Q _{6, respectively,} and the diodes 1 connected to them are D ₁ , D ₂ , D ₃ , D ₄ , respectively. When D _5, D _6, the collector of the switching transistor Q _l to Q ₃ is the positive terminal of the external power supply 16, a switching transistor Q ₄
The emitter of to Q ₆ are respectively connected to one terminal of the external power source 16. The switching transistor Q emitter of _l and the collector of the switching transistor Q ₄ is connected to the first coil provided on the stator 14, the following, the collector of the emitter and the switching transistor Q ₅ of when to quenching transistor Q ₂ is the second The coil of
The emitter and collector of the switching transistor Q ₆ of the switching transistor Q ₃ are respectively connected to the third coil.

The drive circuit 3 turns on the switching transistors Q ₁ , Q ₂ , and Q ₃ in order of 120 ° in electrical angle, and also switches on and off in order of 120 ° in electrical angle with the PWM signal. Q ₄ ,
To turn on the Q _5, Q _6. This switching transistor Q
The driving timing of _l to Q ₆ in FIG. 5 shows a Q _l to Q _6.

In FIG. 1, the switching transistor Q ₄ is turned on and off with the same cycle and duty ratio as the PWM signal during a period from the latter half of the on period of the switching transistor Q ₂ to the first half of the on period of the switching transistor Q _3. Q ₅ during the period same-on from the second half of the oN period of the switching transistor Q ₃ to the first half of the oN period of the switching transistor Q _l,
Off, the switching transistor Q ₆ is period also turned in the second half of the ON period of the switching transistor Q _l until the first half of the ON period switching transistor Q _2, is turned off.

When the motor is started as described above, the Hall element sensors 7A, 7B and 7C detect the rotation of the rotor, and as shown by 7A, 7B and 7C in FIG. As a result, a rotor position signal having a phase difference of 120 ° in electrical angle and a width of 180 ° in electrical angle is generated. These rotor position signals are subjected to processing such as amplification and waveform shaping by a sensor amplifier 8 adjusted to a predetermined gain, and are supplied to the logic circuit 6 of the one-chip three-phase inverter 15.
For example, a rotor position signal generated by, for example, the Hall element sensor 7A is supplied to a rotation speed signal forming circuit 9, and a rotation speed signal representing the rotation speed of the rotor is formed by the frequency or cycle thereof. The rotation speed signal is supplied to the speed correction circuit 10 and is compared with the rotation speed according to a speed command from the outside to form a speed correction signal corresponding to the difference between the rotation speeds. The duty ratio of the PWM signal output from the PWM signal forming circuit 11 is controlled by the speed correction signal.

The logic circuit 6 sequentially turns on and off the switching transistors Q _{1 to} Q ₃ which are also shifted in phase by 120 ° at an electrical angle of 120 ° from the three-phase rotor position signal supplied from the sensor amplifier 8. And the commutation signal (switching signal) from the PWM signal forming circuit 11 having the timing relationship described with reference to FIG.
A switching signal having the same cycle and the same duty as the WM signal is formed and sent to the drive circuit 3.

Thus, the energization time of each coil provided on the stator is controlled in accordance with the duty ratio of the PWM signal corrected by the speed correction signal from the speed correction circuit 10, and the rotation speed of the rotor is controlled by an external speed. Control is performed so as to match the rotation speed according to the command. When the rotation speed of the rotor changes, the period of the Hall element sensors 7A, 7B, 7C also changes accordingly, so that the switching transistors Q ₁ , Q ₂ , Q ₃ turn on the rotor for each 1/3 rotation period. I do.

Thus, the rotation speed of the rotor is PWM
It is determined by the duty ratio of the signal, and by changing this duty ratio, the rotation speed of the electric motor can be changed.

FIG. 6 is an exploded perspective view showing an example of a conventional motor having the circuit configuration shown in FIG. 4 and having a one-chip three-phase inverter mounted therein.
Is a stator core, 19 is a coil, 20 is an aperture, 21A,
21B and 21C are supports, 22 is a shaft, 23A and 2
3B is a bearing, 24 is a rotor, 25 is a printed wiring board,
26 is a peripheral circuit, 27A, 27B and 27C are screws, 28
Is a lead wire, 29 is a lower case, 30A, 30B, 30
C and 30D are open holes, 31 is an outlet, 32 is an open hole, 33
Is a screw, and 34A, 34B and 34C are screw holes.

In FIG. 1, a coil 19 wound around a slot provided on the inner surface of an upper case 17 is provided.
Is fitted into the cylindrical stator core 18. An opening 20 is provided at the center of the upper surface of the upper case 17, and a flange is formed from the lower end of the outer peripheral surface. Four screw holes 34A, 34B, 34C are formed in the flange at equal intervals.
(The other one is not shown). further,
On the outer peripheral portion of the lower surface of the stator core 18, bar-shaped supports 21A, 21B, 21C protruding downward are fixed at equal intervals.

The outer peripheral surface of the rotor 24 is covered with a ferrite-based magnetic material having a thickness of about 2 mm, and a shaft 22 penetrating the center thereof is integrated. This shaft 22
A bearing 23A is fixed to a portion above the rotor 24, and a bearing 23B is also fixed to the lower end of the shaft 22. A printed wiring board 25 through which the shaft 22 passes is disposed between the rotor 24 and the bearing 23B.

The lower case 29 has an opening 32 at the bottom center.
However, a drawer port 31 penetrating through the side surface is provided, and a flange protruding outward is provided at an upper end portion. Openings 30A, 30B, 30C, and 30D are provided at equal intervals in the flange portion. ing.

On the upper surface of the printed wiring board 25, a circuit conductor pattern corresponding to the circuit configuration shown in FIG.
Peripheral circuits 26 such as Hall element sensors 7A, 7B, 7C, one-chip three-phase inverter 15, sensor amplifier 8, and rotation speed signal forming circuit 9 are mounted. The lead wire 28 is connected to the lower surface and connected thereto.

The rotor 24 is inserted into the stator core 18 together with the shaft 22, and the bearing 23A is
7 is fixed to the inner upper surface. Due to the attachment of the rotor 24, the upper part of the shaft 22 is
Stick out to the outside. The printed wiring board 25 is fixed to supports 21A, 21B, 21C protruding from the lower surface of the stator core 18 by screws 27A, 27B, 27C. The lower case 29 is attached to the upper case 17 so as to tightly cover the printed wiring board 25, the stator core 18, and the like. This mounting is performed by opening screw holes 34A, 34B, 34C, 34D (not shown) in the flange portion of the upper case 17 with the openings 30A, 30B, 30C, 3C in the flange portion of the lower case 29.
0D, these openings 30A, 30B, 30C,
Screws 33A, 34B, and 34 are screwed through 30D.
C, 34D. In this case, the bearing 23 </ b> B at the lower end of the shaft 22 is fixed in the opening 32 of the lower case 29, and the lead wire 28 is led out from the inside of the lower case 29 through the outlet 31.

FIG. 7 is a partially developed view of a room air conditioner using such an electric motor as a fan motor. This room air conditioner includes an indoor unit 35 arranged indoors, an outdoor unit 36 arranged outdoors, and a pipe 37 therebetween. The indoor unit 35 includes a tangential flow fan 38A and an outdoor unit 36.
Are each provided with a propeller fan 38B. The above-mentioned electric motors can be used as the electric motors 39A and 39B for driving the fans 38A and 38B. Normally, the three-phase inverter of the motor is approximately the same size as the main body of the motor. However, since the above-described motor has a built-in one-chip three-phase inverter, the control unit of the indoor unit 36 is accordingly increased. Can be downsized, so that the outdoor unit 36
Can also be miniaturized. This is the same for the indoor unit 35.

[0025]

However, since the high power elements such as the switching transistors in the one-chip three-phase inverter are heat generating elements, the one-chip three-phase inverter becomes high-pitched and causes deterioration in characteristics and reliability. And so on. For this purpose, it is necessary to provide a heat dissipation fan in the one-chip three-phase inverter.

However, as described with reference to FIG. 6, on the printed wiring board 25, not only the one-chip three-phase inverter 15 and the Hall element sensors 7A, 7B, 7C, but also a large number of peripheral circuits 26 are mounted. Therefore, there was no space for attaching the heat dissipation fan to the one-chip three-phase inverter 15. For this reason, the output of the electric motor has been limited to about 20 (W).

An object of the present invention is to solve such a problem,
It is an object of the present invention to provide a motor capable of dissipating heat of a built-in three-phase inverter and realizing high output.

[0028]

To achieve the above object, the present invention provides a sensor for detecting rotation of a rotor, a peripheral circuit to which an output signal of the sensor is supplied, and an output signal of the peripheral circuit. Accordingly, a one-chip three-phase inverter that rotationally drives the rotor is disposed on the bottom surface of a case that houses the rotor, the stator, and the like, and the case is used as a heat radiation means of the one-chip three-phase inverter.

As described above, since the case serves as a heat radiating means of the one-chip three-phase inverter, the heat radiating effect of the one-chip three-phase inverter can be sufficiently obtained, and the output of the motor can be increased.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing an embodiment of a motor according to the present invention, and portions corresponding to FIG. 6 are denoted by the same reference numerals.

In this embodiment, the circuit configuration is the same as that of the conventional motor shown in FIG. 4, and the three-phase inverter 15 shown by the one-dot chain line in FIG. Have been. In the following description of this embodiment, the sensor amplifier 8, the rotation speed signal forming circuit 9, the speed correcting circuit 10, the PWM signal forming circuit 11, the starting current limiting circuit 12, and the oscillation circuit 13 are collectively referred to as a peripheral circuit.

In FIG. 1, the one-chip three-phase inverter 15, peripheral circuits, and Hall element sensors 7A to 7C are housed in a lower case 29. For this reason, the printed wiring board 25 used in the conventional electric motor shown in FIG. 6 becomes unnecessary.

Note that two pins 40A and 40B are provided on the lower surface of the flange of the upper case 17, and openings 41A and 41B are provided in the flange of the lower case 29 so as to face these pins. When assembling the motor, the pin 40A is
The pins 40B are respectively inserted into the openings 41B in A, whereby the combination relationship between the upper case 17 and the lower case 29 is set to be constant.

Next, a specific example of mounting each circuit in the lower case 29 will be described with reference to FIG. 2 which is a cross-sectional view of the lower case 29 taken along the line XX '.

In the specific example shown in FIG. 2A, the one-chip three-phase inverter 15 is arranged such that the heat sink on the back surface thereof is in close contact with the bottom surface inside the lower case 29.
It is fixed to this bottom surface by screws 42. Further, a support tool 43 projects from the inner bottom surface of the lower case 29,
A printed wiring board 45 is attached to this by screws 44. On this printed wiring board 45, three Hall element sensors 7 and a peripheral circuit 46 are mounted.
The pins of the one-chip three-phase inverter 15 are connected to predetermined terminals of the circuit conductor pattern on the printed wiring board 45, and the lead wires 28 are connected to other predetermined terminals. Each component housed in the lower case 29 except for the end portion where the detection port of the Hall element sensor 7 has the detection port is molded with the mold resin 47.

As described above, in this specific example, since the lower case 29 serves as a heat radiating means of the one-chip three-phase inverter 15, heat is sufficiently released and the output capacity of the motor can be greatly increased. . In this specific example, the capacity of the conventional electric motor was 40 (W), while the capacity was 20 (W).

Further, since circuit components such as a one-chip three-phase inverter are arranged in the lower case 29 which has been vacant so far, space is effectively used, and it is necessary to provide the printed wiring board 25 as shown in FIG. And the space for this can be reduced, and the motor can be further downsized. According to this specific example, it is possible to reduce the size by about 10% as compared with the conventional electric motor shown in FIG.

Further, since the components housed in the lower case 29 are molded, the position of the Hall element sensor 7 is fixed, and the Hall element sensor 7 is stabilized against vibrations caused by rotation of the rotor 24, and the rotation of the rotor is detected. It is performed stably and reliability is improved.

In the specific example shown in FIG. 2B, a metal substrate 48 provided with a steel circuit wiring pattern via an insulating resin 49 having good thermal conductivity is formed on the inner bottom surface of the lower case 29. The bottom surface of the one-chip three-phase inverter 15 is fixed to a portion where the area of the wiring pattern 51 formed on the insulating resin 49 is increased by a screw 50 so as to be in close contact with the heat sink. Are fixed by the solder 52. The Hall element sensor 7 and the peripheral circuit 46 are also electrically connected to predetermined positions on the wiring pattern 51 by soldering. And
As in the specific example shown in FIG.
Molded with One-chip three-phase inverter 15
Is transmitted to the lower case 29 via the solder 52, the wiring pattern 51, the insulating resin 49, and the metal substrate 48.

In the specific example shown in FIG. 2C, the insulating resin 49 is provided on the inner bottom surface of the lower case 29, and the metal substrate 48 in FIG. 2B is omitted. .

In the embodiment shown in FIG.
The one-chip three-phase inverter 15 is mounted on the inner bottom surface of the lower case 29 as in the specific example shown in FIG.
Further, a flexible circuit board 53 is provided on the bottom surface, and the Hall element sensor 7 and the peripheral circuit 46 are mounted on the flexible circuit board 53.

The same effects as in the specific example shown in FIG. 2A can be obtained in the specific examples shown in FIGS. 2B to 2D.

[0043]

As described above, according to the present invention, (a) the heat radiation of the one-chip three-phase inverter is performed by the case, so that the heat radiation effect can be sufficiently obtained and the output capacity of the motor can be greatly increased. Can be enhanced.

(B) The one-chip three-phase inverter, peripheral circuits, and sensors are stored by effectively utilizing the space in the case, so that the conventionally used printed wiring board becomes unnecessary, and the space for the printed wiring board can be reduced. The size of the electric motor can be reduced.

(D) Since the one-chip three-phase inverter, peripheral circuits, and the sensor are molded with the molding resin, there is no displacement of the sensor with respect to vibration due to the rotation of the rotor, and the rotation of the rotor can be detected stably. In addition, the moisture resistance of each circuit is improved, so that the reliability is improved and the life is prolonged.

Such excellent effects as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a motor according to the present invention.

FIG. 2 is a sectional view showing a storage side of each component in a lower case in FIG.

FIG. 3 is a diagram showing an internal configuration of a one-chip three-phase inverter.

FIG. 4 is a block diagram showing a circuit system of a conventional motor using the one-chip three-phase inverter shown in FIG.

FIG. 5 is an operation explanatory diagram of the conventional electric motor shown in FIG.

FIG. 6 is an exploded perspective view of the conventional electric motor shown in FIG.

FIG. 7 is a configuration diagram of a room air conditioner.

[Explanation of symbols]

 7, 7A, 7B, 7C Hall element sensor 8 Sensor amplifier 9 Speed signal forming circuit 10 Speed correction circuit 11 PWM signal forming circuit 12 Starting current limiting circuit 13 Oscillator 14 Stator 17 Upper case 18 Stator core 19 Coil 22 Shaft 24 Rotor 28 Re 1 wire 29 lower case 43 support 45 printed wiring board 46 peripheral circuit 47 molding resin 48 metal substrate 49 insulating resin 51 wiring pattern 52 solder 53 flexible circuit board

Claims (1)

[Claims] A sensor for detecting rotation of the rotor, a peripheral circuit to which an output signal of the sensor is supplied, and a rotation in accordance with an output signal of the peripheral circuit. An electric motor including a driving one-chip inverter, wherein the one-chip inverter, the sensor, and the peripheral circuit are arranged on a bottom surface in the case, and the case is used as a heat radiating means of the one-chip inverter. Electric motor.